I am sure you can find an old board that supports a Pentium 4, but I think it would be more expensive to find one than to get a new board/CPU/RAM. You could look for a pentium G setup which would be very cheap.
anyway, older ASUS P4C800-E board finally went south. ATX. Uses Pent IV socket 478, RAM is DDR 400 PC 3200, would prefer to avoid having to replace CPU and RAM.
Would appreciate leads to good source for good used or reliably refurbished similar replacement, or for a setup that somebody wants to get rid of.
I know you want to avoid replacement if possible. But I must warn you, that unless the repairs on the board are simple (like a capacitor swap), the costs of diagnosis and repairs on that board will be more than the cost of a new board.
In addition, usually when an old board fails, more than 1 component is about to go bad even if you replace the original component on board that already failed. Cascaded failures are common since on the motherboard, as an example: a blown capacitor usually shorts and puts extra load on the regulators for a prolonged period of time, and this in turn, shortens the lifespan of the regulator IC.
I have done a few board repairs, and quite a lot of them died within months of the previous repair, and it wasn't obvious from a diagnosis point of view what was the component that died eventually (a lot of surface mount ICs to check, labour intensive).